To assess whether proliferation as measured by Ki-67 staining of breast epithelial cells is reduced in women receiving these treatments.

To explore the difference in the expression of other biomarkers (including cleaved caspase-3 [apoptosis marker], ER, vitamin D receptor [VDR], and 1α-hydroxylase) in breast tissue obtained from these women.

To assess whether parathyroid hormone, IGF-1, IGFBP-3, 25(OH)D, and 1,25(OH)D serum levels are altered in these women at baseline and at 6 and 12 months.

To explore whether a change in mammographic density correlates with polymorphisms in the VDR gene.

To assess other sources of vitamin D (sunlight exposure, diet) in these women using a validated questionnaire administered at baseline and at 12 and 24 months.

To collect and bank serum, plasma, and breast tissue from these women before and after a 1-year intervention with vitamin D for future biomarker analysis.

To assess the toxicity of high-dose cholecalciferol compared to placebo in this setting.

Arm I: Participants receive oral cholecalciferol once weekly and oral vitamin D once daily. Treatment repeats for 12 months in the absence of evidence of cancer or unacceptable toxicity.

Arm II: Participants receive oral placebo once weekly and oral vitamin D once daily. Treatment repeats for 12 months in the absence of evidence of cancer or unacceptable toxicity.

Blood samples are collected at baseline and periodically thereafter for biomarkers and 25(OH)D level. Participants undergo a mammogram at baseline and at 12 months. Participants may also undergo random core-needle breast biopsy at baseline and at 12 months.

Participants complete a questionnaire at baseline and at 12 and 24 months.

After completion of study therapy, participants are followed up at 1 and 12 months.

Eligibility

Ages Eligible for Study:

18 Years to 50 Years (Adult)

Sexes Eligible for Study:

Female

Accepts Healthy Volunteers:

No

Criteria

DISEASE CHARACTERISTICS:

At an elevated risk of breast cancer by at least one of the following criteria:

Diagnosis of ADH, ALH, lobular carcinoma in situ (LCIS) or resected ductal carcinoma in situ (DCIS) or small invasive breast cancers (pTmi or pT1a N0) if no pior RT, tamoxifen, or systemic breast cancer treatment within 28 days prior to registration OR diagnosis of resected Stage I (T1b-c N0-N1mi) through Stage II breast cancer for which the participant has been disease-free for at least 5 years and has completed all adjuvant treatment OR

A known* deleterious mutation in BRCA1, BRCA2, PTEN, or TP53 NOTE: *The participant must be a documented carrier to meet this criterion. If there is a known mutation in a hereditary breast cancer susceptibility gene in a participant's family member, the participant herself must have undergone genetic testing as per NCCN clinical guidelines to be eligible per this criterion.

Mammographic density ≥ 50% (heterogenously dense) NOTE: **Risk models are to be used only if there is no known previous diagnosis of resected DCIS or LCIS and there is no known deleterious mutation in BRCA1, BRCA2, PTEN, or TP53.

At least one breast available for imaging and biopsy (a previously irradiated breast [i.e., for resected DCIS] is not evaluable for breast imaging or biopsy)

Baseline mammogram (performed within 10 days after starting their last menstrual period on a digital mammography machine) that shows either normal or benign findings

Less than 6 months since the last menstrual period, no prior bilateral oophorectomy, and no use of hormone-replacement therapy

Has undergone a prior hysterectomy but no prior bilateral oophorectomy AND follicle-stimulating hormone values measured within the past 28 days are consistent with the normal values for the premenopausal state

Zubrod performance status 0-1

Serum creatinine ≤ upper limit of normal (ULN)

Serum calcium or corrected calcium ≤ ULN

Spot urine calcium:creatinine ratio < 0.37 mg/dL

INR ≤ 1.5 times ULN+

PT and PTT ≤ ULN*

Baseline serum 25(OH)D level ≤ 32 ng/mL (or 80 nmol/L)

Not pregnant or nursing

Negative pregnancy test

Fertile patients must use effective contraception

No other prior malignancy except for the following:

Adequately treated basal cell or squamous cell skin cancer

In situ cervical cancer

Adequately treated stage I or II (including resected Stage I, T1b-c N0-N1mi through Stage II breast cancer) from which the participant is currently in complete remission

Any other cancer (including contralateral breast) for which the participant has been disease-free for ≥ 5 years

Concurrent multivitamins allowed provided that the dose of vitamin D in the multivitamin does not exceed 400 IU daily

No concurrent participation in any other clinical trial for the treatment or prevention of cancer unless the participant is no longer receiving the intervention and is in the follow-up phase only (participants must not join such a trial while participating in this study)

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01097278